Integrated scanner on a common substrate having an omnidirectional mirror

ABSTRACT

An integrated scanner for scanning a barcode omnidirectionally is formed an a common substrate. The scanner may include a mirror assembly or scan module, a laser diode, and a detector, mounted on a single substrate or several connected substrates. Lenses can be used to focus a laser beam from the laser diode as well as expand a laser beam deflected by the micro-machined mirror.

RELATIONSHIP TO OTHER APPLICATIONS

This application is a continuation-in-part of Ser. No. 08/506,574, filedJul. 25, 1995, now U.S. Patent No. 6,102,294 which is a continuation ofSer. No. 08/141,342, filed Oct. 25, 1993, now abandoned, which is acontinuation-in-part of Ser. No. 08/111,532, filed Aug. 25, 1993, nowU.S. Pat. No. 5,623,483 which is a continuation-in-part of Ser. No.07/745,776, filed Aug. 16, 1991, now abandoned, which is a continuationof Ser. No. 07/530,879, filed May 29, 1990, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to scanners, and specifically, tointegrated barcode scanners.

Barcodes store information about an associated object and can be read byscanners. As barcode scanners have become smaller, the number of useshave increased. Today, barcode scanners are used to price store items,control warehouse inventory, and even route overnight packages.

In reading a barcode, a barcode scanner scans a laser beam across thebarcode and detects the reflected light from the barcode. Typically,barcode scanners, including handheld scanners, have been constructedusing discrete components. These discrete components, such as laserdiodes and rotatable scanning mirrors, are separately manufactured andcarefully aligned in the scanner to obtain the proper scanning function.

However, the use of discrete components limits further miniaturizationof the barcode scanner, thus restricting additional uses for the barcodescanner. Further, improper alignment of the discrete components canrender the scanner inoperative. Thus, the discrete components must becarefully aligned during assembly, making the scanner complex and costlyto construct.

Accordingly, it is desirable to provide an improved barcode scanner withincreased flexibility.

It is also desirable to provide a miniaturized barcode scanner.

It is also desirable to provide a barcode scanner that is simpler toconstruct.

It is also desirable to decrease the cost of constructing a barcodescanner.

Additional desires fulfilled by the invention will be set forth in thedescription which follow, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theadvantages of the invention may be realized and obtained by means of theinstrumentalities and combinations particularly pointed out in theamended claims.

SUMMARY OF THE INVENTION

To achieve the foregoing desires, a scan module on a common substrateprovides an omnidirectional scan pattern. More particularly, a scanmodule formed on a common substrate consistent with the presentinvention comprises a mirror for scanning light across a target, asupport for coupling the mirror to the substrate, and a means for movingthe mirror to provide an omnidirectional scan pattern across the target.The moving means may include a combination of a magnet and a coil or amirror electrode and a substrate electrode. Alternatively, the movingmeans may include orthogonal hinges, coupled between the mirror and thesubstrate, made of shape memory alloys.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with the description, serve to explain the objects, advantages,and principles of the invention.

In the drawings,

FIG. 1 is a side view of a scanner consistent with the presentinvention;

FIG. 2 is a plan view of the scanner in FIG. 1;

FIG. 3 is a side view of a scan module used in the scanner shown in FIG.1;

FIG. 4 is a side view of another scanner consistent with the presentinvention;

FIG. 5 is a side view of yet another scanner consistent with the presentinvention;

FIG. 6 is a plan view of the scanner in FIG. 5;

FIGS. 7A and 7B show a side view of still other scanners consistent withthe present invention;

FIG. 8 is a perspective view of another scan module consistent with thepresent invention;

FIG. 9 is a side view of yet another scan module consistent with thepresent invention;

FIG. 10 is a top view of still another scan module consistent with thepresent invention;

FIG. 11 is a top view of another scan module consistent with the presentinvention; and

FIG. 12 is a top view of a scanner incorporating a scan moduleconsistent with the present invention.

DETAILED DESCRIPTION

Reference will now be made to methods and apparatus -*consistent withthis invention, examples of which are shown in the accompanyingdrawings. In the drawings, the same reference numbers represent the sameor similar elements in the different drawings whenever possible.

Light scanning systems consistent with the present invention are formedon a common substrate to provide omnidirectional scan patterns. Thelight scanning system may include a light source for producing a lightbeam, a deflector for deflecting the focused light beam in a desiredpattern, a lens, a detector for monitoring the light beam from the lightsource, a sensor for detecting a reflection of the deflected light beam,and electronic circuits.

FIG. 1 shows a scanner 100 including a laser diode 112, spherical lens114, scan module 118, and detectors 120 and 128. Laser diode 112 anddetector 128 are mounted on a laser submount 126, which serves as asupporting stand. Spherical microlens 114 is supported by lens holder116. Laser submount 126, lens holder 116, scan module 118, and detector120 are mounted on a substrate 122.

The surface of substrate 122, which is preferably made of asemiconductor material such as silicon, includes a flat portion 121adjacent to a sloped portion 123.

Preferably, the sloped portion 123 is inclined at about a 45° angle.Laser submount 126 and lens holder 116 are mounted on flat portion 121,and scan module 118 is mounted on sloped portion 123.

Laser diode 112 is aligned with an optical axis of lens 114 and emits avisible laser beam according to a laser diode driver, not shown in thedrawings. In a preferred embodiment, laser diode 112 can be anycommercially available laser diode capable of producing a laser beamsuitable for bar code scanning, such as the laser diode chip from a SonySLD 1101 VS.

Detector 128 is mounted on laser submount 126 behind laser diode 112 formonitoring the output of laser diode 112. Detector 128 creates a signalrepresenting the amount of light from the back of laser diode 112, whichis proportional to the intensity of the laser beam from the front oflaser diode 112. That signal can be transmitted to a laser diode driverto control the output of laser diode 112.

FIG. 1 shows lens 114 secured in an upright position by a separate lensholder 116. Lens 114 and lens holder 116 could also be a singleintegrated device. Although FIG. 1 shows lens holder 116 mounted on theflat portion of substrate 122, it could also be attached to lasersubmount 126. Also, although lens 114 is shown as a spherical microlensin the preferred embodiment, lens 114 could also be any other lens forfocusing a laser beam, such as a ball microlens, a grated rod index lens(GRIN), a micro-FRESNEL lens, or a cylindrical microlens.

The desired focus of the laser beam can be achieved by adjusting thedistance between lens 114 and laser diode 112. Lens holder 116 may beadjustable to move lens 114 with respect to laser diode 112, but lens114 is preferably fixed in a prealigned position.

Scan module 118 intercepts and deflects a laser beam from laser diode112. During operation of scanner 100, scan module 118 scans the laserbeam in one dimension across a target. Scan module 118 preferablycomprises a micro-machined mirror, which is fabricated using existingVLSI technology. K. E. Peterson, “Silicon as a Mechanical Material,”Proc. of IEEE, Vol. 70, No. 5, 420-457 (May 1982), U. Breng et al.,“Electrostatic Micromechanic Actuators,” 2 J. Micromech. Microeng.256-261 (1992), and Larry J. Hornbeck, “Deformable-Mirror Spatial LightModulators,” 1150 Proceedings of SPIE (1989) describe acceptabletechniques for fabricating micro-machined mirrors.

Detector 120, which is preferably mounted on the flat portion 121 ofsubstrate 122, detects a reflection of a laser beam as the beam isscanned across a target. The laser beam scatters as it is scanned acrossthe target, thus allowing detector 120 to receive and detect lightreflected from the target. Detector 120 then creates a signalrepresenting the detected reflection. For example, where a laser beamhas been scanned across a barcode having light and dark regions, thelight regions of a barcode will reflect light, but the dark regions willnot. As the laser beam is scanned across the barcode, detector 120detects the dispersed light, which represents the light regions of thebarcode, and creates a corresponding signal, thus permitting the barcodeto be “read.” In a preferred embodiment, detector 120 is amonolithically integrated photodetector.

FIG. 2 shows a top view of scanner 100. Laser diode 112, lens 114, andscan module 118 are arranged in alignment with each other to permit scanmodule 118 to deflect a focused laser beam. Detector 120 can be locatedon either side of lens holder 116.

Wire bond pads 130 permit detector 120 to interface with an externaldevice, for example, a signal processor. Wire bond pads 132 and 134permit laser diode 112 and detector 128, respectively, to interface withan external device, such as a laser diode driver, for controlling theoutput of laser diode 112. Wire bond pads 142 allow micro-machinedmirror to be actuated by an external device such as a feedback circuit(not shown).

Scan module 118 may be implemented using various structures, such as thetorsional or cantilever structures described in more detail below.Further, scan module 118 can be actuated by various techniques alsodescribed in detail below such as electrostatic actuation and heatactuation. For heat actuation, hinges would be made of shape memoryalloy or be bimetallic.

If it has a torsional structure, scan module 118 includes scanningmirror 136, torsional hinges 138, and frame 140. Hinges 138 aresupported by frame 140, which is mounted on the sloped portion 123 ofsubstrate 122. Scanning mirror 136 is suspended by hinges 138 androtates about an axis formed by hinges 138 along the surface of thesloped portion of substrate 122. Scanning mirror 136 can be rotated upto 90°. As described above, wire bond pads 142 permit scan module 118 tointerface with an external device, such as a scan module driver forcontrolling scan module 118.

FIG. 3 shows various elements for controlling scan module 118.Electrostatic actuation is one way that scan module 118 can rotatemirror 136 to scan an incident laser beam. Preferably, scan module 118includes upper electrodes 144 mounted on a glass cover 148 on eitherside of the rotation axis above mirror 136, and substrate electrodes 146mounted on substrate 122 on either side of the rotation axis belowmirror 136. Upper electrodes 144 should be transparent to allow light toenter and exit scan module 118. For example, upper electrodes 144 can beformed by depositing on glass cover 148 a semi-transparent metalliccoating having a low reflectivity.

During operation of scan module 118, upper electrodes 144 and substrateelectrodes 146 are energized to create an electrostatic force to rotatemirror 136. The electrostatic force creates a voltage between one of thesubstrate electrodes 146 arid mirror 136, which in turn creates chargesof opposite polarity between substrate electrode 146 and mirror 136. Theresulting attractive force pulls the closer side of mirror 136 downward,thus rotating mirror 136 along the rotation axis.

At the same time, a voltage is applied between mirror 136 and acorresponding upper electrode 144 to aid the substrate electrode 146 inrotating mirror 136. The resulting attractive force pulls the other sideof mirror 136 upward, continuing to rotate mirror 136 in coordinationwith the substrate electrode 146.

Mirror 136 can be rotated in the opposite direction by applying voltagesto the other substrate electrode 146 and upper electrode 144. Anincident light beam can be scanned by scan module 118 by alternatelyapplying voltages to the appropriate substrate electrodes 146 and upperelectrodes 144. This approach provides a simple method of actuating scanmodule 118 using very low power consumption.

Although FIG. 3 shows both upper electrodes 144 and substrate electrodes146, mirror 136 could also be rotated using only one set of electrodes,i.e. either upper electrodes 144 or substrate electrodes 146. In such aconfiguration, substrate electrodes 146 could rotate mirror 136 withoutusing upper electrodes 144 by alternately applying voltages between thesubstrate electrodes 146 and mirror 136. Upper electrodes 144 could workalone in the same manner. Either situation would require a greaterattractive force to rotate mirror 136.

Hinges 138 can be made of any suitable material, but are preferably madeof a shape memory alloy, such as titanium nickel, because of the uniqueshape-restoring features of such alloys. Shape memory alloys return totheir original shape when heated above a transition temperature. Afterhinges 138 are twisted by the rotation of mirror 136, they can besubjected to a short electric pulse prior to each scan to heat them andreturn mirror 136 to its original position. A 10-20 mW pulse can beapplied for 10 milliseconds or less to restore mirror 136 to itsoriginal position.

FIG. 4 shows a different embodiment of a scanning system. Scanner 102includes laser diode 112 mounted on laser submount 126 in alignment withan optical axis of lens 144 for emitting a laser beam, and detector 128mounted on laser submount 126 for monitoring the output of laser diode112. Lens 144, supported by lens holder 116, focuses the laser beamemitted from laser diode 112. Laser submount 126 and lens holder 116 aremounted on a flat portion 121 of substrate 122. Scan module 118, mountedon a sloped portion 123 of substrate 122, deflects the focused lightbeam across a target, and detector 120 detects a reflection of thescanned laser beam.

In addition, scanner 102 further includes lens 146, supported by lensholder 142, for magnifying the deflection of the beam from scan module118 before the beam is scanned across a target. A wider deflection ofthe beam allows a smaller mechanical deflection angle of a micromirrorin module 118 and increases the flexibility in focusing the beam. Asshown in FIG. 4, lens 144 is a positive lens and lens 146 is a negativelens, although lenses 144 and 146 can be of any suitable type.

FIG. 5 shows another embodiment of the invention as scanner 104comprising laser diode 112 mounted on laser submount 126, which is inturn mounted on flat portion 121 of substrate 122. Detector 128 is alsomounted on laser submount 126 behind laser diode 112 for monitoring theoutput of laser diode 112. Scan module 118, mounted on the slopedportion 123 of substrate 122, receives an unfocused laser beam fromlaser diode 112 and deflects that beam through lens 148, which issupported by lens holder 150. Lens 148 focuses the deflected beam beforeit reaches a target, such as a barcode. The configuration of scanner 104provides a simple and compact structure due to the absence of a lensbetween laser diode 112 and scan module 118.

FIG. 6 shows a top view of scanner 104 without lens 148. Laser diode 112is aligned with scan module 118. Wire bond pads 132 and 134 allowexternal devices to interface with laser diode 112 and detector 128,respectively. Wire bond pads 142 allow external devices to interfacewith the micro-machined mirror. Although FIG. 6 shows no detector fordetecting the reflected light, such a detector may easily be mountednear scan module 118 or at some other desirable location.

Another scanning system, shown in FIGS. 7A and 7B, bends the light beamonto a scan module. Scanners 106 and 107 (FIGS. 7A and 7B, respectively)comprise laser diode 112, lens 114, scan module 118. Lens 114 used inscanners 106 and 107 can be of any type and is mounted on substrate 222,which is completely flat. Laser diode 112 is mounted on laser submount126.

As shown in FIG. 7A, laser diode 112 of scanner 106 is aligned above anoptical axis of lens 114 by an amount ×. By aligning laser diode 112 inthis way, the laser beam emitted from laser diode 112 is bent downwardan angle θ. The bent laser beam strikes scan module 118, which ismounted on flat substrate 222. Scan module 118 scans the laser beamacross a target in the manner described in the other embodiments.

As shown in FIG. 7B, scanner 107 also includes a prism 115 positionedadjacent to lens 114. A laser beam emitted from laser diode 112 passesthrough lens 114 and is bent downward by prism 115 onto scan module 118.Again, scan module 118 scans the laser beam across a target in themanner described in the other embodiments.

Bending the laser beam emitted from laser diode 112 eliminates the needfor a sloped substrate. This provides a distinct advantage because aflat substrate is easier to manufacture than a sloped substrate.

Scan modules 118 and 119 can also include miniature scan elementscapable of producing a number of omnidirectional scan patterns. Theseelements can be built using a combination of micromachining, die, andwire bonding techniques or other available methods.

FIG. 8 shows a scan module 250 for producing omnidirectional scanpatterns consistent with the present invention. Scan module 250 includesa small mirror 136 connected to substrate 222 by an elastic support 252,such as a polyimide. Four magnets 254 are placed on individual sides ofthe back of mirror 136 as shown in FIG. 8. In addition, four coils 256are incorporated into substrate 222, for example by etching, directlyunder magnets 254.

Applying current through coils 256 attracts and repels magnets 254 tosubstrate 222. The combination of attraction or repulsion by magnets 254provides mirror 136 with omnidirectional motion for generatingomnidirectional scan patterns. For conventional, i.e., notmicro-machining, technology, a ball-joint type of support can be used inplace of elastic support 252.

FIG. 9 shows another scan module 350 consistent with the presentinvention similar to the one described above in accordance with FIG. 8.Scan module 350 in FIG. 9 uses one or more mirror electrodes 353 placedon the back of a mirror 136 instead of magnets. Scan module 350 of FIG.14 further includes a support 352 for connecting mirror 136 to asubstrate 322, a wire 351 for applying an electric potential to mirrorelectrode 353, and a set of four substrate electrodes 355 (only threeshown) incorporated into substrate 322.

To provide omnidirectional scan patterns, an electric potential isapplied between substrate electrodes 355 and mirror electrode 353 tomove mirror 136. The electric potentials between each substrateelectrode 355 and mirror electrode 353 generate electrostatic forcesthat cause mirror 136 to move in different directions, thereby providingan omnidirectional scan pattern.

FIG. 10 shows another scan module 450 consistent with the presentinvention. In scan module 450 of FIG. 10, a mirror 136 is suspended onfour orthogonal hinges 462. The hinges are made of, for example, shapememory alloys (SMA). Also shown are alternate hinges 464, also made ofSMA, which suspend mirror 136 from different points. In addition, asupport 452 can be installed under mirror 136. Support 452 provides apivoting point for mirror 136 and can serve as a motion limiter if thereis a sudden acceleration, such as being dropped.

Hinges 462 provide the omnidirectional scan capability to mirror 136.When heated by applying current, hinges 462 change their dimension andmove mirror 136 to create an omnidirectional scan pattern.

FIG. 11 shows a scan module 500 that includes a combination of elementsused in scan modules 250, 350, and 450 (FIGS. 8, 9, and 10,respectively). In contrast to those scan modules, however, scan module500 only has two active elements. As shown in FIG. 11, scan module 500includes a mirror 136 and a support 552 for supporting mirror 136 andconnecting it to a substrate 522. Scan module 500 further includes, twoSMA hinges 502 and an optional pivot hinge 504. Pivot hinge 504 connectsto the corner of mirror 136 and can be used as a suspension or as aconductor to provide electric potential to one or more mirror electrodes(not shown).

Scan module 500 can provide omnidirectional scan patterns using theoperation of any of the above scan modules 250. For example, SMA hinges502 could be replaced by a combination of coils and magnets as describedin scan module 250 of FIG. 8. By applying current through the coils, themagnets are either attracted to or repelled from the substrate. Thecombination of attraction or repulsion by the magnets with support frompivot hinge 504 provides mirror 136 with omnidirectional motion forgenerating omnidirectional scan patterns.

Alternatively, SMA hinges 502 could be replaced by two substrateelectrodes. In this design, pivot hinge 504 is used as a conductor toprovide electric potential to mirror electrodes (not shown). To provideomnidirectional scan patterns, mirror 136 is moved by applying electricpotential between the substrate electrodes and mirror electrode.Electrostatic forces, based on the electric potentials between eachsubstrate electode and the mirror electrodes, cause mirror 136 to movein different directions.

With SMA hinges 502 as shown in FIG. 11, pivot hinge 504 connects tomirror 136 to keep mirror 136 suspended. In operation, SMA hinges 502are heated by applying current. Because hinges 502 are made of SMA, theheat causes hinges 502 to change their dimension, thereby providingmotion to mirror 136 for creating the omnidirectional scan patterns.Each design of scan module 500 only requires two active elements, eithertwo SMA hinges, two combinations of a coil and a magnet, or twosubstrate electrodes.

FIG. 12 shows a scanner 700 integrated on a substrate 702. Scanner 700includes a light source 704, such as a laser diode, a detector 706 fordetecting light reflected from a target, and a scan module 708 forscanning light from light source 704 across the target. Scan module 708may be any of the scan modules discussed above including scan modules118, 119, 250, 350, 450, and 500. Scanner system 700 may be, forexample, a stationary barcode scanner or a handheld barcode scanner.

The scanners of the present invention can be manufactured using eithermonolithic integration or hybrid integration. Monolithic integrationfabricates the opto-mechanical system entirely on a single semiconductorchip. On the other hand, a hybrid integrated circuit combines one ormore individually fabricated subsystems on a common substrate. Hybridintegration generally involves less complicated processes thanmonolithic integration and permits the combination of more accuratedevices.

Many of the components of the present invention including the laserdiode, detectors, lenses, and scan module could be fabricated using VLSItechnology. If monolithic integration is used, all of these componentsare fabricated onto a single chip in a single series of process steps.If hybrid integration is used, each component is individually fabricatedand mounted onto a common substrate.

All of the components need not be VLSI, however. For example, the lensfor focusing the light beam could be constructed using other knowntechniques and then appropriately mounted onto the scanner.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the scanner consistent withthe present invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. A micro-machined scan module formed on a commonsubstrate, comprising: a mirror for scanning light across a target, themirror having a reflecting surface; a support member connected to acenter of the mirror opposite from the reflecting surface for supportingand connecting the mirror to the substrate; and means for moving themirror to scan the light in an omnidirectional scan pattern across thetarget, wherein said moving means includes: a set of magnets, eachlocated at a different edge of the mirror; and a set of micro-machinedcoils for generating a magnetic field, each integrated on the substratebelow a respective one of the magnets.
 2. A scan module according toclaim 1, wherein said moving means further includes current means forselectively applying current to the coils to move the respective magnetabove the coil and provide omnidirectional movement to the mirror.
 3. Ascan module according to claim 2, wherein said set of magnets includesfour magnets and wherein said set of coils includes four coils.
 4. Ascan module according to claim 2, wherein said set of magnets includestwo magnets located at adjacent edges of the mirror and wherein said setof coils includes two coils each aligned with a different one of themagnets.
 5. A scan module according to claim 4, further comprising: aconnector coupled to the substrate and to a corner of the mirror to keepthe mirror suspended above the substrate.
 6. A scan module according toclaim 5, wherein said connector includes a pivot hinge.
 7. Amicro-machined light scanning system formed on a common substrate,comprising: a light source, mounted on the substrate, for producing alight beam; a detector for detecting light reflected from a target; anda scan module for scanning the light beam across the target, the scanmodule including: a mirror for scanning the light beam across thetarget, the mirror having a reflecting surface; a support member coupledto the mirror for supporting and connecting the mirror to the substrate;and means for moving the mirror to scan the light beam in anomnidirectional scan pattern across the targets; wherein said means formoving includes a set of magnets, each one of the set of magnets beinglocated at a different edge of a surface of the mirror opposite to thereflecting surface; and a micro-machined set of coils, each one of theset of coils integrated on the substrate below a respective one of themagnets.
 8. A light scanning system according to claim 7, wherein saidmoving means further includes current means for selectively applyingcurrent to the coils to move the respective magnet above the coil andprovide omnidirectional movement to the mirror.
 9. A light scanningsystem according to claim 8, wherein said set of magnets includes fourmagnets and wherein said set of coils includes four coils.
 10. A lightscanning system according to claim 8, wherein said set of magnetsincludes two magnets located at adjacent edges of the mirror and whereinsaid set of coils includes two coils each aligned with a different oneof the magnets.
 11. A method for providing an omnidirectional scanpattern across a target, comprising the steps of: producing a light beamfrom a light source on a common substrate; directing the light beamtowards a mirror mounted on the common substrate; moving the mirror by amechanism on the common substrate to deflect the light beam in anomnidirectional scan pattern across the target, said moving stepincluding: selectively applying current to a set of micro-machined coilsintegrated on the common substrate to move a set of magnets, each magnetof the set of magnets being located at a different edge of the mirrorabove a respective one of the coils thereby providing omnidirectionalmovement to the mirror.